I. Field of the Invention
The present invention relates generally to lifting devices and, more particularly, to a device for lifting office partitions.
II. Description of the Prior Art
Many office buildings include modular partitions which define the workspaces for the employees working in the building. These modular partitions, however, present special difficulties during the installation of flooring, such as carpet, ceramic tile or the like.
When flooring is to be installed in an office building having modular partitions, it has been the previously known practice to disassemble the office partitions, install the flooring, and then reassemble the office partitions. This procedure, while effective in operation, is disadvantageously very time consuming and thus very expensive in labor costs. Furthermore, any error during the reassembly of the office partition can and oftentimes will create additional difficulties for the employee.
In order to eliminate the necessity of disassembling the office partitions prior to the installation of the flooring and the subsequent reassembly of the office partitions following the flooring installation, there have been previously known lifts designed to slightly elevate the partition without disassembling the partition. Furthermore, only a slight elevation of the office partition, e.g. a quarter of an inch, is necessary to permit the installation of the flooring. Examples of these previously known partition lifts are shown in U.S. Pat. No. 5,299,779, issuing Apr. 5, 1994, as well as U.S. Pat. No. 4,846,443, which issued on Jul. 11, 1989.
These previously known partition lifts included a housing having a lever pivotally mounted at one end to a midpoint of the housing. A lift bracket designed to extend under the office partition was then attached to the other end of the lever.
In order to pivot the lever about its pivotal point, and thus vertically displace the lifting bracket, a piston and cylinder assembly had one end secured to the housing and a second end pivotally secured to the lever about an axis parallel to, but spaced radially from, the pivotal connection of the lever with the housing. Consequently, extension and retraction of the piston and cylinder arrangement simultaneously articulated the lever which, in turn, vertically displaced the left bracket and office partitions in the desired fashion.
There have, however, been a few disadvantages with these previously known partition lifts. A primary disadvantage of these previously known partition lifts is that, when the partition lift is used to raise a very heavy office partition, the end of the housing most spaced from the lift bracket lifts up from the ground due to the torsional force exerted on the housing by the weight of the partition. Such lifting of the housing not only renders the partition lift more difficult to use, but can even cause a dangerous situation in the event that the lift bracket abruptly disengages from the office partition. Such disengagement of the bracket from the office partition can also cause damage to the partition lift.
The present invention provides a partition lift which overcomes all of the above-mentioned disadvantages of the previously known devices.
In brief, the partition lift of the present invention comprises a housing having a main body portion and spaced apart base legs on opposite sides of the main body portion. The base legs are adapted to be supported by a ground surface. Furthermore, the main body portion is spaced upwardly from the base legs at one end of the housing to form an open channel between the main body portion and the base legs at one end of the housing.
An elongated lever is then pivotally mounted at one end of the lever to a midpoint of the housing. This lever is pivotal about a first pivot axis.
A piston and cylinder assembly has one end secured to the other end of the housing and the other end of the piston and cylinder assembly pivotally attached about a second pivot axis to the lever. The second pivot axis is parallel to but radially spaced from the first pivot axis between the lever and the housing. Consequently, extension and retraction of the piston and cylinder assembly vertically displaces the other end of the lever relative to the housing.
A lift bracket assembly is attached to the end of the lever most spaced from the first pivot axis. This lift bracket assembly may take any of several forms necessary such that a portion of the bracket assembly extends underneath the partition to be lifted. In one embodiment, a plate is attached to the other end of the lever. One or more hangers are then adjustably mounted to the plate such that a tab portion of the hanger extends underneath the partition to be lifted. The horizontal adjustability of the hangers relative to the plate enables the hangers to be properly positioned to avoid damage to the partition and/or achieve the most sufficient lift of the partition in operation.
A torsion bar assembly is then disposed in the channel between the housing main portion and the spaced apart base legs. This torsion bar assembly includes an elongated rigid bar having an upper surface in abutment with the bottom of the housing main portion. At least two, and preferably four, threaded fasteners are then threadably mounted on opposite ends of the torsion bar. These fasteners, furthermore, abut against an upper surface of the base legs. Thus, upon tightening of the threaded fasteners, the torsion bar assembly creates an outward force between the base legs and the main housing portion in a generally vertical direction.
The torsion bar assembly thus preloads the tension between the base legs and the housing main portion. When lifting a heavy partition, the torsion bar, by preloading the tension between the base legs and the housing main portion, ensures that the base legs remain flatly in contact with the ground support surface during the entire lifting operation.
The partition lift of the present invention enjoys further design enhancements over the previously known partition lifts. For example, a handle is secured to the main housing portion about a midpoint for easy transport of the partition lift. Similarly, non-friction pads can be applied to the bottom of the base legs so that, by using multiple lifts on a single partition, upon elevation of the partition by the lifts, the lifts together with the partition may be horizontally slid along the ground support surface.